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-   -   Transmission and Pinion Angles (http://www.hotrodders.com/forum/transmission-pinion-angles-228212.html)

1brewmaster1 01-10-2013 12:29 PM

Transmission and Pinion Angles
 
Can some one PLEASE set me straight on setting the proper angles on the output shaft of the transmission and pinion. I have read so many discussions about this and it becomes confusing to understand.

1951 Chevy Pick-up, 700R4, leaf springs, 1972 Chevy truck differential.

Everything was fine until I replaced the leaf springs. The original springs were pretty flat and the new ones are bowed properly. I now have a rake to the front end. It now vibrates at 65-70. Previously, I set the transmission at 3* down and the pinion at 3* up and everything was fine. Now, I can't raise the transmission far enough to get to the 3* down position. Currently the transmission is at 7* down. I did not build the truck so I am stuck with what I have. If I raise the transmission any further, I pick up all kinds of rattles and vibrations from the drive line touching the body.

Can I keep the transmission at 7* down and set the pinion at 7* up to cancel harmonics?

Thanks in advance for your comments.

kso 01-10-2013 01:14 PM

I don't really understand the degrees-down and degrees-up description...and how that works with the truck being raised...

...but at the heart of it and however the body sits, the centerline of the trans output shaft and the centerline of the pinion shaft need to be parallel with each other as seen from the side.

NEW INTERIORS 01-10-2013 01:18 PM

Quote:

Originally Posted by 1brewmaster1 (Post 1633099)
Can some one PLEASE set me straight on setting the proper angles on the output shaft of the transmission and pinion. I have read so many discussions about this and it becomes confusing to understand.

1951 Chevy Pick-up, 700R4, leaf springs, 1972 Chevy truck differential.

Everything was fine until I replaced the leaf springs. The original springs were pretty flat and the new ones are bowed properly. I now have a rake to the front end. It now vibrates at 65-70. Previously, I set the transmission at 3* down and the pinion at 3* up and everything was fine. Now, I can't raise the transmission far enough to get to the 3* down position. Currently the transmission is at 7* down. I did not build the truck so I am stuck with what I have. If I raise the transmission any further, I pick up all kinds of rattles and vibrations from the drive line touching the body.

Can I keep the transmission at 7* down and set the pinion at 7* up to cancel harmonics?

Thanks in advance for your comments.

When I set up my cars I set the carb base level.. On a chevy motor with the carb base level it will put the Trans shaft down 3*.. Then depending on what rear suspension and what I will be using the car for...I set it to what I'm using... But your right about 3* down on the trans and 3* up on the pinion.. If your 7* down, Then 7* up should work.. Now.. To be able to set the carb base level you say you will be hitting the body... Can't you raise everything with the body mounts to get it right..

sedanbob 01-10-2013 04:58 PM

1 Attachment(s)
I'm having a little trouble visualizing your situation. If the transmission was 3 down and the original rear 3 up, then the new springs raised the back of the chassis, that should have reduced the angle that the transmission was down, not increased it. It should now be closer to level (or raised slightly above level). Without changing anything else, adding lowering blocks to the rear (equal to the increase because of the new springs) should return everything to the previous alignment. You would probably need to use an angled block to adjust the pinion angle now, lowered or not.


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